Various locking devices have heretofore been proposed.
For example, U.S. Pat. No. 3,889,497 relates to a multiple-lock securing system including a locking plate which contains openings with locks positioned therein. The bar can be fastened to the locking plate when the locks are positioned in each of the openings. When one of the locks is removed from the locking plate the bar is released which provides access to the secured area.
Moreover, U.S. Pat. No. 3,703,821 relates to a safety lock provided with a number of apertures capable of receiving individual workmens' padlocks and controlled by a master key so that the workmen may work on a machine with the knowledge the that the power cannot be switched inadvertently by another workman.
Moreover, U. S. Pat. No. 4,466,259 discloses a locking device for locking a cap onto the filling neck of a tank.
Another device described in U.S. Pat. No. 4,085,599 teaches a padlock adapter assembly comprising a pair of identically stamped plates each having a pair of spaced passages aligned with a respective passage in the other plates to form a pair of aligned passages for receiving a respective padlock shackle.
Finally, U.S. Pat. No. 3,667,259 discloses another variation of a safety lock.
Many of such locking devices have been designed to receive a plurality of padlocks to be individually opened by a number of different persons or workmen so that the secured area which may include a fuse box, restricted area or the like, may only be entered once all of said padlocks have been removed.
In some other cases, such locking devices are provided so that if a particular person such as a mechanic, electrician or maintenance man is repairing a machine such locking device is secured to the machine so that another workman may not inadvertently start same while the other is maintaining said machine.
Such devices present relatively complicated structure which have limited utility particularly since some of the locking devices can be pried open.
It is an object of this invention to provide an improved locking device which substantially reduces deliberate tampering of said locking device.
The broadest aspect of this invention relates to a locking device comprising; a hasp rod having two limb portions and a pair of locking plates hingedly connected together along one of said limb portions of said hasp rod, said plate adapted for relative swinging movement between an open position where said plates permit access to said other limb of said hasp rod, and a closed position where said locking plates clasp said other limb of said hasp rod between said plates, said plates including aligned passages for receiving a plurality of padlocks to lockingly secure said plates in said closed position.
It is another aspect of this invention to provide a locking device comprising; a hasp rod having a curved rod portion presenting first and second cylindrical limbs extending from the ends of said curved rod portion; a pair of rectangular locking plates hingedly connected together to said first limb, said plates adapted for relative swinging movement between an open position where said plates permit access to said second limb of said hasp rod, and a closed position where said plates clasp said second limb of said hasp rod between said plates, said plates including aligned passages adapted to receiving a plurality of padlocks to lockingly secure said plates in said closed position.